In the field of electronics there is competitive pressure among manufacturers to drive the performance of their equipment up while driving production costs down and maintaining acceptable yield and reliability. This is especially true for packaging of dice on substrates, where problems with flux overspray reduce yield and/or increase throughput time.
Flux overspray causes non-uniform thickness on a substrate bump field, resulting in die misalignment during reflow. Non-uniform thickness in the solder bump region may also cause non-wetting of solder bumps. Additionally, if excess flux extends onto die-side lands, the solder paste may also be contaminated. Such problems lead to reduced yield, as misaligned dice are typically scrapped.